Latch assemblies for motor vehicles are generally well-known in the art. In most motor vehicles, a hood is used to enclose the engine or luggage compartment of the motor vehicle. Such hoods are typically situated so as to be opened from the front of the vehicle and hinged along a rearward edge, such that the hood opens from the front of the vehicle. The hood is typically equipped with a striker attached to the lower surface near the forward edge of the hood. The striker is situated to interact and to be restrained by the latch assembly attached to the motor vehicle chassis, likewise located proximate the forward edge of the hood. As is common in the industry, a latch release handle is typically situated in the occupant compartment, typically near the driver's side kick panel or under the instrument panel. The handle is typically connected via a bowden cable to a latch release lever operatively connected to a primary latch of the latch assembly. Upon actuation of the hood release handle in the occupant compartment, the bowden cable pulls on the latch release lever, thereby releasing the striker from the primary latch of the latch assembly.
A secondary hood latch is also common in such latch assemblies. Such secondary hood latches must be manually operated while in front of the vehicle, such that in the event of an inadvertent release of the primary latch handle or failure of the primary latch while the vehicle is in motion, the hood will not abruptly raise due to wind pressure. Rather, the secondary latch requires a person standing in front of the vehicle to manually operate the secondary latch to free the hood striker from the secondary latch of the latch assembly, thereby allowing the hood to be fully raised, providing access to the engine in the engine compartment and/or luggage within the luggage compartment.
In the context of such latch assemblies having primary and secondary hood latches, the deployment module disclosed herein addresses and solves the problem of pedestrian head injuries occurring in the event of a frontal impact by a motor vehicle. These head injuries are primarily caused by the pedestrian's head impacting the vehicle hood subsequent to the initial collision event. That is, pedestrians are generally hit at the legs first, with the body then rotating about an axis parallel to the vehicle lateral axis, followed by the head impacting the hood. However, given the trend to package engine components more efficiently within the engine compartment, very little clearance is provided between the lower surface of the motor vehicle hood and the upper rigid portions of the engine components, particularly such components as the intake manifold and air cleaning assemblies. Thus, in the event of an impact by the pedestrian's head against the hood, there is very little displacement that the hood can provide before encountering a substantially rigid structure that would prevent further deflection of the hood. Similarly, when a pedestrian's head impacts the edges of the hood, there is very little underhood clearance. Thus, the impact force and resulting trauma are magnified in the event of pedestrian injuries.
Heretofore, hood latch assemblies responsive to the presence of a pedestrian have been devised, although they experience certain drawbacks. For example, many prior art hood latch assemblies have rather complicated constructions, which are expensive to manufacture and difficult to repair. Such systems require a redesigned new latch to accommodate the desired function. Other systems have relatively large footprint that tend to obstruct air flow and cooling. Also, such prior art system suffer from higher part count, package complexity, weight, and cost. Hence, a hood latch assembly which overcomes these drawbacks would be advantageous.
The hood latch deployment module disclosed herein particularly accomplishes the foregoing by adapting the present typical motor vehicle latch assembly described above through an add-on module that can be applied to existing designs. The present invention takes advantage of existing structural configurations and uses a sensing device available in many vehicles today, such as radar or other sensing devices that might be used to detect the presence of a pedestrian in the front of the vehicle. At the onset of detecting a pedestrian in front of the vehicle while the vehicle is in forward motion, the sensing device generates a signal that is sent to an actuator, such as a solenoid, situated in and attached to the deployment module to release a resilient member, such as a torsion spring, that in turn releases the primary latch and raise the hood.
Thus, the solution presented by the present disclosure is a relatively low-cost, add-on latch deployment module that abruptly raises the hood by releasing the primary latch and raising the hood to the secondary latch position upon detection of the presence of a pedestrian in front of the vehicle while the vehicle is in forward motion, before the pedestrian head impacts the hood. In some vehicles, for example, the hood is raised approximately 25 mm at the front edge of the hood. When the pedestrian's head impacts the hood, the raised hood allows additional displacement and deflection, thereby absorbing and dissipating greater energy over a longer displacement, thus reducing the amount of force to and energy absorbed by the pedestrian's head and concurrently reducing the trauma to the pedestrian's head. Since the hood is allowed to deflect to a greater total displacement, a head impacting the hood will decelerate over a longer period of time, with lower deceleration levels resulting in less severe head injuries.